MS Bookings - How to register a staff member with a different domain as Admin

1. Staff with the Admin role must be internal users in the same Microsoft 365 tenant and have a Microsoft 365 account. In Bookings, Admin and Viewer roles are explicitly described as roles for staff members who have a Microsoft 365 account, while Guest is for staff who do not.
   • Administrator / Admin: “Staff member has a Microsoft 365 account” and can edit all settings, add/remove staff, and create/edit/delete bookings.
   • Viewer: “Staff member has a Microsoft 365 account” and can see their own bookings, receive invitations, reminders, and change notifications.
   • Guest: “Staff member doesn’t have a Microsoft 365 account” and can be assigned to deliver services but cannot access Bookings.
   If the user is treated as a Guest (for example, because they are not recognized as an internal Microsoft 365 user for that tenant), the role will be locked to Guest and cannot be changed to Admin.
2. Users who are not in the same tenant (true external users) can only be assigned as Guest staff. Guest staff can receive meeting invitations and notifications but cannot access or administer Bookings.
3. Requirements for assigning the Admin role to a staff member:
   • The person must be in the same Microsoft 365 tenant as an internal user.
   • They must have a Microsoft 365 account in that tenant (Bookings uses this to grant Admin/Viewer capabilities).
   • They must be added as staff with a role of Administrator/Admin or Viewer (these roles are only available for internal accounts; Guest is for non‑M365 or external users).
4. For a user with a different domain who is already registered in the same tenant, the steps to have them as Admin are:
   • Ensure that the account is an internal Microsoft 365 account in the tenant (not just an external/guest account). Internal staff are the ones for whom Admin/Viewer roles are available.
   • Add them from the organization directory when using Add staff (type their name, select them from the search results so the fields auto‑populate). When Bookings recognizes them as an internal Microsoft 365 user, the Admin role can be selected and saved.
   • If the account is only present as a guest/external account (no Microsoft 365 license in the tenant), Bookings will treat it as Guest and the role will remain locked to Guest.

If the goal is to give someone full administrative control over a booking mailbox without making them bookable staff, full access and send‑as permissions can be granted via Exchange Online PowerShell instead of using the Bookings staff Admin role.

References:

• Create your staff list
• Add team members to Bookings
• Add staff to your booking calendar in Microsoft Teams
• Shared Bookings Frequently Asked Questions (FAQ)